Pesticide use in the United States has increased greatly in the last 50 years, but the health effects of pesticide exposure are still unclear. Effects of acute, high-level exposures on neurologic function are well- documented. We are planning a cross-sectional study of the neurologic effects of chronic, low-level exposure. We will study farmworkers, who are potentially highly exposed. The study will be conducted in central Florida, in collaboration with the Farmworkers Association of Florida, a grassroots organization representing farmworkers. Participants will be identified from the membership list of a local Credit Union and recruited by staff of the Farmworkers Association. Approximately 95% of the participants will be Hispanic; both men and women will be included. 200 exposed workers from three types of agriculture -- ferns, nurseries, and citrus -- will be compared to 100 control workers with relatively little experience in agriculture. Exposure to pesticides will be assessed using a structured in-person interview which will collect information about lifetime history of farmwork, pesticide poisoning, and pesticide hygiene as well as work practices in specific types of agriculture. Neurologic function will be assessed using a battery of tests, including neurobehavioral tests of cognitive and psychomotor function, tests of vision, a test of vibrotactile sensitivity to evaluate peripheral neuropathy, and a test of postural sway, to assess equilibrium. Polymorphisms in genes involved in pesticide metabolism will also be studied, to evaluate the role of genetic susceptibility. The results of this study will elucidate the effects of pesticide exposure on neurologic function and also address the health problems of an underserved minority group.